The present invention relates generally to vehicle diagnostic systems and methods, and, more particularly, to diagnostic scan tools operative to access diagnostic information from a vehicle electronic control unit (ECU), and to derive a most likely vehicle solution therefrom.
An On-Board Diagnostic, or OBD, system is a computer-based system that was developed by automobile manufacturers to monitor the performance of various components on an automobile's engine, including emission controls. Modern vehicles typically have a vehicle diagnostic system, including one or more modules. Examples of such computer control modules (also known as just “modules”) are: a power train control module (PCM), an engine control module (ECM), a transmission control module (TCM), an ABS control module and an air bag control module. Upon detection of any malfunction, the OBD system provides the owner of the automobile with an early warning indicator (such as illuminating the, check engine light in the dashboard of automobile).
Contemporary ECU's are operative to monitor the operating conditions of various onboard systems and electrical devices to identify and report any defective conditions. Such ECU's have become increasingly sophisticated in their ability to store data related to various defects and to communicate such information to diagnostic tools in communication with the ECU.
OBD was primarily introduced to meet EPA emission standards but through the years, OBD systems have become more sophisticated. For example, in the mid 1990's OBD 2, Standard Edition was implemented in light-duty cars and trucks. OBD 2 provides a plurality of sensors to monitor malfunctions in the engine, chassis, body, and accessory devices. In a simple scenario, the OBD system detects a malfunction in the engine (or any other component that is monitored by sensors of the OBD system) and signals a warning indicative of such a malfunction. For example, a check engine light could be illuminated in an automobile's dashboard indicative of such malfunction. The automobile's owner, upon noticing such a warning indicator, can make plans for taking the automobile to a service station where the malfunction can be further investigated.
Upon arrival at the service station, a repair personnel can connect a cable that serves as a communications link between the automobile's diagnostic port and computing device (such as a code reader, scan tool or laptop). Once connected, the computing device decodes OBD 2 system signals (such as diagnostic trouble codes [DTC] received via the diagnostic port), and presents them to the service station personnel who can then make a decision respecting how to fix the malfunction.
Off-board devices, such as portable code reader/scan tools have been marketed for retrieving and interpreting vehicle diagnostic data. Code readers are generally more simple devices which only scan and display the problem diagnostic codes. More expensive scan tools would have to be used to retrieve live data and perform live tests on the automotive system. The more recent handheld test devices have added circuits for testing systems such the charging system and scanning circuitry wherein live data can be requested for and received.
Scan tool and code readers are governed by a number of standards, e.g. SAE J1978 Rev. 1998-02 and SAE J1979 Rev. 1997-09. Compared to code readers, scan tools are relatively expensive diagnostic devices that have a larger number of features.
There are different types of scan tools. An “OBD 2 Scan 45 Tool” complies with the above-identified specifications. By contrast, a “Manufacturer-Specific Scan Tool” is a scan tool that accesses and displays proprietary manufacturer-specific data (and may also access and display OBD 2 data).
Examples of such manufacturer specific data includes Device Controls on General Motors vehicles; On-Demand Tests in Ford vehicles; and Actuator Tests, Sensor Tests, Interrogator, and Read Temporary Codes in Chrysler vehicles. In general, air bag data, ABS data, cruise control data, and climate control data are also considered to be proprietary manufacturer-specific data and are typically accessible only by Manufacturer-Specific Scan Tools.
In contrast with a scan tool, a code reader is a relatively basic off-board device that links with one or more computer modules in a vehicle diagnostic system via a vehicle computer network, reads any diagnostic trouble codes (referred to as “diagnostic codes” herein) generated by the vehicle diagnostic system and displays any diagnostic codes on a display. Typical code readers do not perform the following major functions that are performed by typical scan tools: “View Data,” also known as “Live Data,” “Freeze Frame Data,” and “Data Test, DTC”, collectively referred to as “freeze frame data” (viewing and displaying data, such as captured fixed data and real-time live, changing data from a plurality of module sensors), display of textual diagnostic descriptions corresponding to the various diagnostic codes, recording and playback of data, device control (manually controlling modules for diagnostic purposes), and reading and displaying vehicle information from the vehicle's computer (e.g. VIN information, controller calibration identification number, etc.). The data typically includes values (e.g. volts, rpm, temperature, speed, etc.) and system status information (e.g. open loop, closed, fuel system status, etc.) generated by the vehicle sensors, switches and actuators. (Digital Can OBD 2 Scan Tool Manual p. 40).
Currently, companies such as Innova Electronics Corporation have combined the scan tool and code reader into a single handheld devices, such as the Enhanced OBD 2 Scan Tool. The Enhanced OBD 2 Scan Tool by Innova Corp. is typical of scan tools wherein the problem diagnostic trouble codes (DTCs) are displayed. All of the live data may also be displayed. However, the live data can amount to several hundred readings which a user may need to scan through in order to receive the problem readings.
Due to the increasing complexity of vehicle electrical systems and components, many of which are made by companies other than the manufacturer and utilize different operating protocols, sorting and evaluating the available vehicle information can be a daunting task. Aftermarket scan tools face the challenge of being able to access and process information not only from the ECU, but also from various associated electrical devices. Moreover, given the inter-relatedness of vehicle electrical systems and onboard devices, defects in relation to one onboard electrical device may be reflected in other electrical devices, resulting in multiply digital trouble codes, the ultimate cause of which may be yet another device or circuit that does not directly correspond to any of the digital trouble codes identified in the ECU. The inherent complexity of such systems is compounded by the number of different makes and models of vehicles that are available, and the changes to those vehicles over the years that they are offered. For aftermarket scan tools to have a practical value to ordinary consumers, the scan tools must be relatively inexpensive and typically constructed as a handheld device that is simple to operate.
The numerous challenges to the development of such consumer friendly scan tools have encouraged scan tool manufacturers to consistently seek new ways for accessing, interpreting, processing vehicle diagnostic data, to accurately identify vehicle defects and to derive reliable solutions thereto.
As described below, one implementation of the present invention is directed to a scan tool, and method of the scan tool operation, which leverages the capabilities of contemporary ECUs to derive and process certain diagnostic data, in conjunction with indexed databases that enhance the ability to communicate with the onboard electrical devices and the processing of data derived therefrom.
Another implementation of the present invention utilizes historical information respecting the operation of vehicle systems and electrical devices as a further basis to identify and evaluate vehicle defects and the most likely solutions therefore.
These and other objects and advantages associated with the present invention are described in more detail below, in conjunction with the appended drawings and claims.